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    <title>GraphExplorer Help File</title>
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      <h1>Help for GraphExplorer</h1>

      <h2>Graphical User Interface</h2>

      <h2>Generating New Graphs</h2>
      <p>
      Currently, the application has support for generating <b>empty</b>, <b>circle</b>,
      <b>star</b>, <b>wheel</b>, and <b>complete</b> graphs.
      In addition, a <img src="./random-uniform24.png"></img><b>uniform random graph</b> may be generated (directed or undirected) using either
      (i) a number of nodes and probability of edge,
      or (ii) a number of nodes and a number of edges.
      A <img src="./random-pref24.png"></img><b>preferential attachment graph</b> may be generated, using a small initial uniform      random graph as a seed, in which each vertex is added with either
      (i) a fixed number of connections,
      or (ii) a variable number of connections (with a user-specified probability distribution).
      </p>

      <h2>File Types</h2>
      Currently supported file types include:
      <ul>
          <li><b>Edge list</b> format: each line consists of a pair of integers indicating the edge between two nodes.</li>
          <li><b>Pajek</b> format (.net): vertex declarations (with positions), and a variety of input formats for edges, including edge lists and adjacency matrices.</li>
          <li><b>Extended pajek</b> format (.netx): pajek format with additional custom file information
          <li><b>UCINet</b> format (.dat): supports more general data structures
      </ul>
      Note that only part of these formats is currently supported! In the future, we hope to add support
      for both <b>GraphML</b> and <b>DyNetML</b> formats.

      <h2>Visualization Features</h2>
      Many visual settings may be adjusted using the property panel at left.

      <h3>Longitudinal Graphs</h3>
      This application supports longitudinal graphs, which change over time. A sample longitudinal graph
      may be created using the "preferential attachment" random graph generator, and selecting the
      longitudinal option. Special features included with the longitudinal view include:
      <ol>
          <li>A slider below the main graph that displays the time frame for the longitudinal graph, which
            may be adjusted dynamically. If a dynamic layout is active, the layout automatically reconfigures
            for the new graph.</li>
          <li>A chart displaying the value of the selected metric over time. For this to be active, one or
            more nodes must be highlighted: use the <code>Layout -> Highlight Nodes</code> to select these nodes.</li>
      </ol>

      <h2>Layout Methods</h2>
      Supported layouts are summarized here.

      <h3><img src="./layout-circle24.png"></img>Circular Layout</h3>
      Places nodes around a circle.
      <h3><img src="./layout-random24.png"></img>Random Layout</h3>
      Places nodes at random within a box.
      <h3><img src="./layout-spring24.png"></img>Spring layout</h3>
      Uses simulated physics to generate ideal locations for nodes and edges. Forces include
      (i) a repulsive force between each pair of vertices,
      (ii) an attractive force between each pair of connected vertices, and
      (iii) a global force ensuring components stay close to the middle of the screen.

      <h2>Metrics</h2>
      Currently, one metric at a time may be displayed along with the graph. The metric displays
      in several ways:
      (i) the node sizes on the main plot are adjusted to have areas proportional
      to that node's metric value,
      (ii) the actual metric values are displayed on the main graph table, and
      (iii) a chart & table of the distribution of metric values is shown at bottom.
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